1. Field of the Invention
The present invention relates to a solid-state imaging device and an imaging device which are examples of a semiconductor device for physical quantity distribution detection. Specifically, the present invention relates to an arrangement wherein multiple unit configuration elements are arrayed which has sensitivity as to an electromagnetic wave input externally such as light or a radiation beam for example, and reads the physical quantity distribution converted to an electrical signal by the unit configuration elements as an analog electrical signal or digital data. Particularly, the present invention relates to an arrangement having a function to thin out and output pixels at the time of reading an image signal.
2. Description of the Related Art
A physical quantity distribution detecting semiconductor device made up of an array of multiple unit configuration elements (for example pixels), in a linear form or in a matrix form, which have sensitivity as to physical quantity change such as an electromagnetic wave input externally such as light or a radiation beam, or pressure (such as contact), is employed in various fields.
As an example, in the field of picture devices, a solid-state imaging device is used which employs an imaging element (imaging device) of a CCD (Charge Coupled Device) type which detects changes to the light (one example of an electromagnetic wave) which is an example of physical quantity, or an MOS (Metal Oxide Semiconductor) or a CMOS (Complementary Metal-oxide Semiconductor) type.
In recent years, as an example of a solid-state imaging device, image sensors of an MOS type or CMOS type which can overcome various problems which a CCD image sensor has, have been gaining attention.
For example, a method called column parallel output type, or column type, is widely used, wherein a CMOS image sensor has an amplifying circuit made up of a floating diffusion amplifier for each pixel or the like, wherein upon the reading of a pixel signal, as an example of address control, a certain row from the pixel array unit is selected, the one row worth is simultaneously accessed and the pixel signals are read simultaneously in parallel from the pixel array in increments of rows, i.e. all of the pixels of the one row worth are simultaneously read in parallel.
Also, in the field of computer equipment, fingerprint authentication devices and the like are employed, which detect an image of a fingerprint with information relating to fingerprints, based on changes to electrical features based on pressure or changes to optical features. A physical quantity distribution which has been converted to an electrical signal by unit configuration elements (pixels with a solid-state imaging device) is read out as an electrical signal.
Also, among solid-state imaging devices, there is an amplifying-type solid-state imaging device which has pixels in a configuration of amplifying-type solid-state imaging elements (APS; Active Pixel Sensor, also called gain cells) having a driving transistor for amplification at the pixel signal generating unit which generates a pixel signal according to a signal charge generated at the charge generating unit. For example, many of the CMOS-type solid-state imaging devices have this sort of configuration.
In order to read a pixel signal to the outside with such an amplifying solid-state imaging device, an arrangement is made wherein address control is performed as to the pixel unit wherein multiple unit pixels are arrayed, and signals from individual unit pixels are selected in a determined address order or arbitrarily, and read out. That is to say, the amplifying solid-state imaging device is an example of an address control type of solid-state imaging device.
For example, with an amplifying solid-state imaging device which is one type of an X-Y address-type solid-state imaging device wherein unit pixels are arrayed in a matrix form, pixels are configured employing an active element (MOS transistor) with an MOS configuration or the like, in order for the pixels themselves to have an amplifying function. That is to say, the signal charge (photoelectron or hole) accumulated in the photodiode which is a photoelectrical converter is amplified with the above-mentioned active element, and read out as image information.
As tendencies for solid-state imaging devices in recent years, miniaturization and increase in speed of the pixels is significant. A shared problem herein is that of sensitivity. The miniaturization of the former relates to decreased incident light amount per pixel from the shrinking of the light-receiving unit. Also, the increase in speed of the latter relates to decrease in incident light amount from the reduction in exposure time.
Regarding the former, an arrangement is known, for example, wherein the are occupied by the circuit is decreased by a portion of the circuit which is held within each pixel cell is shared among multiple pixels, whereby the area of the photoelectric converter is secured (hereafter this will be called a pixel sharing method).
With Japanese Unexamined Patent Application Publication No. 2006-054276, an arrangement is proposed wherein one voltage converter is disposed between two photoelectric converters which are diagonally adjacent within a 2-dimensional array (pixel array unit and imaging unit), and the one voltage converter is configured to be shared by two photoelectric converters, whereby the occurrence of an invalid region being generated on the periphery of the voltage converter is suppressed, thereby securing the regional area of the photoelectric converters as to the pixel area, and the photoelectric converters are disposed at the optical center of each pixel, and the optical pixel center is disposed 2-dimensionally with even spacing.
Further, as to the latter, a thinning reading is known as an example of a high-speed method for shortening the readout processing time of a pixel signal, which only reads a portion of the pixel signals instead of reading pixel signals from all of the pixels of the pixel array unit (imaging unit) (for example, see Japanese Unexamined Patent Application Publication No. 2006-054276). With Japanese Unexamined Patent Application Publication No. 2006-054276, a mode is shown to perform thinning in increments of rows or in increments of columns, as an example.
In PCT Japanese Translation Patent Publication No. WO2003/079675, thinning reading is described as being employed for processing to reduce the number of pixels according to the situation, such as reading all pixels at the time of photographing a still image but thinning out the number of pixels at the time of photographing a moving image to perform reading at a high speed, for example.